No mental health professionals who treated Lanza suspected that he would ever commit the type of horrific act he committed last Dec. 14, when he killed his mother, then drove to Sandy Hook Elementary School and killed 20 students and six educators

Lanza killed himself within one minute of police officers responding to the school.

Those were among the key findings of a report released Monday by the office of Danbury State’s Attorney Stephen Sedensky III, who is charged with criminal investigations in the Western Connecticut district that includes Newtown.

The document released Monday is not a complete or final recounting of the shootings. A much longer state police report, expected to be thousands of pages long, still has not been released, and it’s not clear when that report will come out.

But the summary released Monday unveils several key details about that morning and about Lanza’s life.

The summary said it was clear that Lanza “intentionally committed horrendous crimes, murdering 20 children and 6 adults in a matter of moments, with the ability and intention of killing even more.”

Police said Lanza’s actions were planned, including his suicide.

All of the shootings were done with a Bushmaster rifle, while Lanza killed himself with a single shot from a Glock 20, 10 mm pistol in a classroom. He killed his mother, Nancy, by firing four shots with a .22 caliber Savage Mark II rifle in her bed at their home at 36 Yogananda Street in the Sandy Hook section of Newtown.

All of the guns Lanza used were legally purchased by his mother.

Had Lanza survived, he would have been charged with 26 counts of murder under special circumstances, two counts of attempted murder and one count of murder.

There is no clear indiction why he killed and why he targeted Sandy Hook Elementary School.

Nancy Lanza told a friend on Dec. 10, 2012, that Adam Lanza had “bumped his head badly” and that there was some bleeding, “but he was okay.”

The previous month, Nancy Lanza had informed her son of her intention to move to North Carolina, and was discussing with him whether he would move to Washington state to attend “a special school,” or get a computer job in North Carolina.